锶原子互组跃迁谱的实验研究

观测了热原子束中锶原子(5s²)¹S₀—(5s5p)³P₁ 互组跃迁的荧光谱和饱和荧光谱, 实验测定了不同的参量下 ⁸⁸Sr(5s²)¹S₀—(5s5p)³P₁ 互组跃迁荧光谱. 研究结果表明: 不同的实验参数(温度、激光光强、激光扫描频率)对谱线有较大的影响, (5s5p)³P₁态的长寿命特点导致谱线强度随激光扫描频率呈倒数关系变化; 由于Doppler增宽, 渡越增宽等因素的影响, 谱线线宽远大于其自然线宽且随激光扫描频率呈正比关系变化.     

Transport coefficients of quasicrystals

The transport coefficients for the nine point groups —which represent the symmetry groups of the quasicrystals in two and three dimensions—have been evaluated and tabulated in this work, employing group-theoretical methods.     

Theoretical study on decay of the 4d core-excited states of Cs III

In a recent XUV photoabsorption spectrum of Cs Ⅲ ions by Cummings and O＇Sullivan [2001 J. Phys. B 34 199], rather large linewidths were found for the 4d^95s^25p^6 - 4d^105s^25p^5 transition which are quite in disagreement with corresponding quasi-relativistic multiconfiguration Hartree Fock （MCHF） calculation. In the present work, a detailed multiconfiguration Dirac-Fock study has been carried out to explore this discrepancy. Owing to the detailed consideration of electron correlation effects, some ‘forbidden＇ Auger decay channels, such as 4d^105s^25p^35d and 4d^105s^05p^6, would become ‘open＇. As a result, remarkable improvement of the linewidths has been obtained in our calculation. Furthermore, the theoretical Auger spectrum of the 4d^ 95s^25p^6 core-excited states of Cs Ⅲ ions is Riven in the present work.     

Electron-impact excitation out of the metastable levels of krypton

We have measured the electron-impact excitation cross sections out of the two metastable levels of Kr into the ten levels of the 4p(5)5p configuration. For a common 4p(5)5p final level, the peak excitation cross sections out of the two individual 4p(5)5s metastable levels are found to differ by 1 to 2 orders of magnitude. This is explained by the special features of the electronic structure of the two configurations involved. The peak cross sections are 10 to 1600 times larger than the corresponding peak cross sections out of the ground state.     

Application of retrospective time integration scheme to the prediction of torrential rain

The retrospective time integration scheme presented on the principle of the self-memory of the atmosphere is applied to the mesoscale grid model MMS,constructing a mesoscale self-memorial model SMMS, and then the shortrange prediction experiments of torrential rain are performed in this paper. Results show that in comparison with MM5 the prediction accuracy of SMM5 is obviously improved due to its utilization of multiple time level past observations,and the precipitation area and intensity predicted by SMM5 are closer to observational fields than those by MM5.     

Competition of Concentration Narrowing and Power Broadening of a Dark Resonance in a Ladder System of Rubidium Atoms: Specificities of Its Occurrence in Thin Spectroscopic Cells

Optics and Spectroscopy - The effect of electromagnetically induced transparency (EIT) in a three-level ladder system 5S1/2‒5P3/2 –5D5/2 of Rb atoms is investigated. The effect of...     

采用高信噪比电磁诱导透明谱测定~(85)Rb原子5D_(5/2)态的超精细相互作用常数

基于~(85)Rb原子5S1/2-5P3/2-5D_(5/2)阶梯型能级系统(780 nm+776 nm),利用高信噪比的电磁诱导透明谱对~(85)Rb原子5D_(5/2)态超精细分裂进行测量.其中,频率校准是通过位相型电光调制器和共焦法布里-珀罗腔共同实现的.通过测量~(85)Rb原子5D′5/2态(F′=5),(F′′=4)及(F′′=3)之间的超精细分裂,我们确定了~(85)Rb原子5D_(5/2)态的磁偶极超精细相互作用常数(A=-(2.222±0.019)MHz)和电四极超精细相互作用常数(B=(2.664±0.130)MHz).     

圆偏振飞秒激光脉冲与低压氙气体靶相互作用软X射线辐射实验研究

利用平场光栅谱仪,分别在2和3 kPa的低气压下,测量了脉宽35 fs的圆偏振超强超短激光脉冲与5 mm长氙气体靶相互作用产生的波长在5～60 nm范围内的离子谱线。2 kPa时最强的跃迁为XeⅧ：4d105s(2S_1/2)—4d95s5p(2P_3/2)的17.085 6 nm线,3 kPa时最强的跃迁为11.343 nm的XeⅦ 4d105s2(1S0)—4d95s25f(3P₁)跃迁。两种气压下,Xe均被电离到XeⅦ,XeⅧ,XeⅨ态。     

Theoretical study of structures of Ga5N5 cluster

The structures and energies of a Ga₅N₅ cluster have been calculated using a full-potential linear-muffin-tin-orbital (FP-LMTO) method, combined with molecular dynamics technique. Twenty-four structures for a Ga₅N₅ cluster have been obtained. The most stable structure is a C₁ planar structure with a N₃ subunit. The Ga₅N₅ clusters show a preference for a N₃ subunit, revealing the same behavior as in the Ga₃N₃ and Ga₄N₄ clusters. The existence of strong N–N bonds dominates the structure of a Ga₅N₅ cluster. Through the calculation of the density of states we found that the most stable structure of Ga₅N₅ clusters presented semiconductor-like properties.     

The probabilities of radiative transitions and lifetimes of levels in the spectra of Cu XX,La IV

The probabilities of radiative electric dipole transitions 2p ⁵3p, 2p ⁶–2p ⁵3s, and 2p ⁵3d in the spectrum of neon-like copper Cu XX and 5p ⁵6p, 5p ⁶–5p ⁵6s, 5p ⁵7s, and 5p ⁵5d in the spectrum of xenon-like lanthanum La IV are calculated. The wave functions of the intermediate coupling were found from the wellknown experimental energy levels by the least-squares method (LSM). To transfer to an absolute scale the radial integrals for the transitions calculated in the form of a length on the Hartree–Fock functions have been used. By summing the calculated probabilities of the transitions, the lifetimes of the levels of configurations 2p ⁵3s, 2p ⁵3p, and 2p ⁵3d in the spectrum of Cu XX and levels of configurations 5p ⁵6s, 5p ⁵6p, and 5p ⁵7s in the spectrum of La IV have been obtained.     

Theoretical Study of the Electronic States of the Rb(2) Molecule

We have calculated the electronic states of Rb(2) by multireference configuration interactions using the averaged relativistic effective small-core potential and the core-polarization potential. The potential energy curves for a large number of states dissociating into from 5s+5s up to 7s+5s asymptotic limits are calculated and the spectroscopic constants are reported. The spin-orbit effects for the states dissociating into 5p+5s and 4d+5s are calculated using the effective spin-orbit potential. The results are compared with available experimental data and other theoretical works. Copyright 2001 Academic Press.     

Radiative constants in the spectra of ions of the krypton isoelectronic sequence

The probabilities of the 4p ⁶,4p ⁵5p→4p ⁵(4d+5s) radiative transitions and the radiative lifetimes of the 4p ⁵4d,4p ⁵5s, and 4p ⁵5p levels are calculated semiempirically for the RbII-MoVII isoelectronic sequence.     

利用铷原子双光子跃迁产生420nm蓝光的实验研究

本实验通过饱和吸收方法获得了铷原子5S_(1/2)→5 P_(3/2)单光子跃迁光谱,并进一步研究了铷原子5S_(1/2)→5 P_(3/2)→5 D_(5/2)的双光子跃迁光谱。使用780nm的控制光和776nm的信号光反向共线作用到铷泡中,通过探测6 P_(3/2)→5S_(1/2)自发辐射产生的420nm蓝光信号得到铷原子5S_(1/2)→5 P_(3/2)→5 D_(5/2)双光子跃迁光谱,利用法布里-珀罗干涉仪测量了~(87)Rb和~(85)Rb的5 D_(5/2)激发态超精细能级,详细研究了铷泡温度和776nm信号光功率对~(87)Rb 5S_(1/2)(F=2)→5 D_(5/2)双光子跃迁光谱的影响。该研究工作为基于原子分子精密光谱测量提供了实验基础。     

Study of a Selective Photoionization Scheme of 177Lu

Optics and Spectroscopy - The hyperfine structure of transitions in the three-step scheme 5d6s22D3/2–5d6s6p4F $$_{{5/2}}^{^\circ }$$ –5d6s7s4D3/2– (53 375 cm–1)...     

Study of the d-f Emission,and f-d Ground-State and Excited-State Absorption of Nd3+ in Crystals Using the Simple Model

The simplified model for 4f-5d transitions is applied to obtain the line strengths for emission, ground-state absorption and excited states absorption involving 4f-5d transitions of Nd³⁺ in crystals. The results are host independent for the usual case where 5d crystal-field interaction can be considered as strong, in the sense that the calculated 5d-4f emission relative line strengths will be the same for Nd³⁺ in any host. Also the calculated 4f-5d absorption line strengths can be grouped by the 5d crystal-field components. For each 5d crystal-field component, the group of absorption line strengths for different 4f²5d transition final states forms a pattern independent of the 5d crystal-field component and the host. For practical cases, due to strong but still limited 5d crystal-field splitting, the transitions to different 5d crystal-field components may overlap each other. The theoretical results are used to interpret available experimental data.     

PLGA/G5-T纳米纤维对重金属离子Hg~(2+)的吸附研究

在制革、冶金、电镀、采矿等行业发展过程中,含有重金属离子的废水进入河道和农田,重金属污染越来越受到人们的重视,治理和回收重金属也成为一个亟待解决的难题。其中重金属离子Hg~(2+)被认为是最毒的重金属。为了有效处理含重金属离子Hg~(2+)的废水,将胸腺嘧啶(Thymine)修饰到第五代聚酰胺-胺树状大分子(G5.NH2)表面,得到G5-T,之后将G5-T与聚乳酸羟基乙酸(PLGA)混合并用静电纺丝方法得到PLGA/G5-T混纺纤维,并用傅里叶变换红外光谱(FTIR)、扫描电镜(SEM)等手段对PLGA/G5-T混纺纤维进行了表征,并以电感耦合等离子体发射光谱仪ICP-OES为检测手段,研究PLGA/G5-T对Hg~(2+)的吸附效果。FTIR结果表明,PLGA/G5-T纤维中3 320cm~(-1)处的氨基吸收峰比PLGA/G5上的弱,在1 660cm~(-1)处的酰胺基吸收峰比PLGA/G5强,说明G5.NH2与胸腺嘧啶~(-1)-乙酸成功反应。SEM结果表明,添加了G5-T混纺而得的PLGA/G5-T平均直径为(751±72)nm,纤维形貌均一,表面光滑无粘连,说明G5-T的加入没有破坏纤维的完整性。ICP-OES研究发现,PLGA/G5-T纤维膜对Hg~(2+)的脱除效率明显高于PLGA/G5纤维膜,胸腺嘧啶显著增强了PLGA/G5-T纤维膜对Hg~(2+)的脱除效率;对多种金属离子的吸附实验结果显示,PLGA/G5-T纤维膜对Cu2+,Cd2+和Co2+有微弱的吸附效果,但其对Hg~(2+)吸附效果显著,PLGA/G5-T纤维膜对水溶液中的Hg~(2+)有选择性吸收功能。研究为开发新型Hg~(2+)吸附剂提供了一种新方法。     

Ho(0.5)Yb(5)氟氧化物玻璃的直接上转换增敏发光

本文研究了HoYb共掺氟氧化物玻璃的直接上转换增敏发光现象。发现了位于 (5 4 4 5nm ,1836 5cm- 1 )和 (6 5 8 5nm ,15 186cm- 1 )的两条很强的上转换发光 ,它们是 5S2 → 5I8和5F5→ 5I8的荧光跃迁。还有其他的一些上转换发光5F3→ 5I8,5S2 → 5I7和5I4 → 5I8的跃迁。还发现存在一种特征的饱和现象 ,即所有上转换发光随激光功率变化的F P双对数关系曲线都是一条相当好的直线 ,其斜率会随着光斑的增大而增大 ,由分析得知这是由能量扩能散造成的。     

Calculation and interpretation of IR and resonant raman spectra of 5-halosubstituted uracils

We have used valence optical theory to carry out calculation and analysis of in-plane vibrations and intensities of IR spectra for isolated 5-fluorouracil and 5-bromouracil molecules. We give a complete interpretation of the corresponding bands in the absorption spectra. We have carried out a quantum mechanical calculations of the relative intensities in the resonant Raman spectra of 5-fluorouracil and 5-chlorouracil. The calculated spectra for the molecular models obtained agree quantitatively with the experimental spectra, and reproduce the observed characteristic spectral differences in the series of molecules: uracil, 5-fluorouracil, 5-chlorouracil, and 5-bromouracil. The models obtained for the molecules can be used for calculation and analysis of the spectra of other halosubstituted nucleic acid bases. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 437–442, July–August, 2006.     

Role of helium in a He-Xe plasma

The populations of the 5p⁵6s and 5p⁵6p levels of Xe are reported as functions of current and partial pressure of He for the positive column of a glow discharge at medium pressures. The populations of the first ones (especially the metastable 5p⁵6s³P₂ one) decrease as the He pressure is raised, whereas those of the upper 5p⁵6p levels increase. An explanation is proposed for the observed changes in the level populations.We are indebted to Professor A. N. Tekuchev for direction and comments, and to Z. P. Gasko for help with the measurements.     

Electronic structure and the Fermi surface of PuCoGa5 and NpCoGa5

Using a relativistic linear augmented-plane-wave method, we clarify energy band structures and Fermi surfaces of recently discovered plutonium-based superconductor PuCoGa5 and the isostructural material NpCoGa5. For PuCoGa5, we find several cylindrical sheets of Fermi surfaces with large volume, similar to CeMIn5, while for NpCoGa5, the Fermi surfaces are found to be similar to those of UMGa5. These similarities are discussed based on the j-j coupling scheme, suggesting some hints for the superconducting mechanism in HoCoGa5-type f-electron compounds.